High velocity multipiece tuyere and method of constructing same

ABSTRACT

A high velocity tuyere having an outer member made of a first material, and formed with ribs and passageways, and an inner member made of a second material having a lower heat transfer coefficient than the outer member, the inner member being disposed within the outer member to provide a leak-free convolute-shaped passage.

United States Patent Inventor Appl. No.

Filed Patented Assignee Lawrence G. Maloney Munster, Ind.

May 7, 1969 Mar. 30, 1971 Inland Steel Company Chicago, Ill.

HIGH VELOCITY MULTIPIECE TUYERE AND METHOD OF CONSTRUCTING SAME 6 Claims, 8 Drawing Figs.

U.S. Cl 266/41, 165/169 Int.Cl C2lb 7/16 Field of Search 122/66,

[56] References Cited UNITED STATES PATENTS 3,351,335 11/1967 Slagley 266/41 3,341,188 9/1967 Armour et al. 266/41 Primary Examiner-James M. Meister AtI0rney-Merriam, Marshall, Shapiro & Klose ABSTRACT: A high velocity tuyere having an outer member made of a first material, and formed with ribs and passageways, and an inner member made of a second material having a lower heat transfer coefficient than the outer member, the inner member being disposed within the outer member to provide a leak-free convolute-shaped passage.

Patentefl March 30, 1971 2 Sheets-Sheet 1 Patented March 30, 1971 3,572,675

2 Sheets-Sheet 2 5 INVENTOR ATTORNEY llilllGIil VELOCITY MULTIPEECE TUYERE AND METHOD OF CONSTRUCTIN G SAME This invention relates to air blast nozzles, and more particularly to tuyeres employed in blast furnaces, and a method of constructing the same.

In blast furnace operations, circulating water cooling systems are employed in tuyeres in order that the heat transferred from the blast furnace to the tuyeres is carried away by the high velocity tuyeres such as is described in the previously mentioned patent, the temperature of theair drops by as much as 45 as it passed through the tuyere at a high velocity. This heat drop in the air is developed due to a heat exchange which occurs between the air and cooling medium passing through a cooling medium passage. While cooling of the tuyere is necessary, the cooling of the hot blast air is an undesirable side effect because in order to offset the hot air heat loss, more coke must be added to the blast furnace to develop the heat lost by the air to the tuyere cooling medium. In a typical furnace operation this results in an increase of about $30-$50 per day in operating costs. Attempts have been made to minimize the hot blast heat loss by providing a refractory material on the inner perimeter of the tuyere, but such attempts have not been generally successful since the refractory material does not hold up over an extended period of time, and eventually cracks and falls off, thereby exposing the inside wall of the tuyere.

A further problem arises in the construction of prior art high velocity tuyeres, wherein the tuyere is cast in one-piece with the intricate convoluted cooling water passageway formed integrally with the casting. Because of limited access, the inspection of the passageways in such'one-piece castings is very difficult. Thus, wires, sand cores, metal shavings and imperfections are often found in castings which passed inspection. As an example, one casting which passed inspection was found to actually contain the following imperfections:

l inch outside wall instead of flinch;

1 1/16 inch inside wall instead of Vzinch;

- and a thin restriction across the water passage caused by a shifting of the core.

Therefore, in accordance with the principles of the present invention there is provided a high velocity tuyere and a method of construction, which tuyere provides efficient cooling of the tuyere itself and yet obviates the undesirable heat loss in the blast air passing through the tuyere.

In accordance with one aspect of the present invention there is provided a high velocity tuyere having an outer member preferably made of copper formed with alternating ribs and passageways within the inner perimeter of said outer member, and including a tubelike inner member of stainless steel or other metal having a lower heat transfer coefficient than the first outer member. The outer wall of the inner member upon assembly of the two members contacts the projecting ribs within the inner perimeter of the first member to provide a leak free substantially convolute shaped passage.

In utilizing the principles of the present invention in practice, it has been found that since the stainless steel insert has a heat conductivity 1/26 that of copper, in a 2,000 F. hot blast system, the hot blast temperature to the furnace is increased by f F.

In accordance with the method aspect of this invention there is included the steps of casting the outer member of the tuyere of copper or copper alloy with the casting having projecting ribs defining open passageways within the inner perimeter of the cast member, so that the passageways can be easily inspected for any obstructions or imperfections in the casting, and inserting a tubular shaped member within the inner perimeter of the cast member, the inner member being formed of stainless steel or other metal dissimilar to the metal in the casting and having a lower heat transfer coefficient than the casting member, the inner member contacting the projecting ribs so as to form sealed convolute passages within the combined assembly of the outer cast member and the inner tubular member. In addition to the ease of inspection of the open passages in the casting, an additional advantage in utilizing the stainless steel insert is the relative ease in which slag can be removed from the inner walls of the sleeve as compared with the all copper tuyere utilized in the prior art, as the slag does not bond as readily to the steel as it does to copper.

The invention will be better understood from the following detailed description thereof taken in conjunction with the accompanying drawings in which:

FIG. I is a perspective view illustrating a multipiece tuyere before assembly thereof, and as constructed in accordance with the principles of the present invention;

FIG. 2 is a cross-sectional view taken along section line 11-" of FIG. 1; i 7

FIGS. 3--7 are fragmentary sectional views illustrating various examples of alternative mechanical interconnections between the outer cast member and the inner sleeve;

FIG. 8 is a fragmentary sectional view illustrating another embodiment of the present invention illustrating a laminated liner for the inner portion of the sleeve.

Referring now to FIG. I, there is illustrated a multipiece tuyere l0 constructed in accordance with the principles of the present invention and illustrated in an exploded view before final assembly. The tuyere 10 includes a one piece outer cast member 12 having a nose end 14 which extends into the blast furnace and a head end 16, and an inner tubular sleeve member 18 insertable into the casting 12 as illustrated in FIG. 2. The outer member 12 is preferably formed of a one piece copper or copper alloy casting which includes the projecting ribs 20 extending from the inner face 22 to define cavities or open passages 2d between the adjacent ribs. The passages 24 are provided in the casting 12 so as to ultimately form the convolute passages for the cooling water which will be supplied to the inlet port 26 and removed through the outlet port 28 in the manner as is illustrated in the previously mentioned patent.

The inner sleeve 18 is formed of stainless steel or other metal dissimilar from the metal used in the casting 12 and having a lower heat transfer coefficient to minimize the amount of heat loss between the hot blast air passing through the inner portion 30 of the sleeve 18 and the cooling medium in passages 24.

In assembling the inner sleeve 18 within the casting 12, the casting is heated while the sleeve I8 is cooled by dry ice or other suitable means and then inserted within the casting in the position as illustrated in FIG. 2. Upon shrinkage of the casting and expanding of the tubular shaped sleeve 18, a tight, shrink fit will occur. Each end 32 of the inner sleeve 13 may then be welded or braised to a corresponding end 34 of the outer casting 12. Referring to FIG. 2, it must be especially noted that the outer surface 36 of the stainless steel member 18 only contacts the ridge or free end portion 38 of the projecting ribs 20, thereby enabling only a minimum of metal to metal contact between the outer casting l2 and the inner sleeve member 18.

The inner member 18 sealingly engages the free end 38 of the projecting ribs 20 to provide a leakproof, substantially convolute passage 24 for the cooling water between inlet port 26 and outlet port 23. The thermal coefficient of expansion of the stainless steel inner member 18 is slightly higher than the copper or copper alloy outer casting 12 so the that the inner member forms a tight sealing engagement with the ribs 20 during normal furnace operation. However, it is also possible to utilize a metal or metal alloy for the inner member lfiwith a lower thermal coefficient of expansion than the outer casting 12, since during normal furnace operation the inner member becomes hotter and will therefore expand close to its limit, thereby still insuring a reliable seal with the ribs 20.

FIGS. 3-7 illustrate various alternative techniques for interconnecting the inner sleeve insert 18 within the casting 12. In FIG. 3, the casting 12 is fonned with the final rib 40 at the nose end of the tuyere such that the inner sleeve 18 projects with the respective end 32 immediately above the last casting rib 40 and is welded or braised thereto at the perimeter location 42. One advantage of the specific arrangement of FIG. 3 is to enable only the stainless steel sleeve 18 to encounter the hot air blast within the tuyere.

In FIG. 4 the casting 12 is formed in a similar manner with the last rib 40 as in FIG. 3, however, the stainless steel insert 18 extends only to slightly overlap the rib 40. A second sleeve 44 is inserted within the tuyere and the casting 12, and sleeve 18 are secured by the welding or braising 46 within the inner perimeter of the tuyere.

In FIG. 5, the casting 12 is formed as previously shown in connection with FIG. 2, with an additional cavity 48 at the nose end 34. The sleeve 18 Similarly contains a projecting portion 50 which matches the contour of the cavity 48 so that the insert 18 can be interlocked to the casting 12 by means of silver solder 52.

FIGS. 6 and 7 illustrate alternative techniques for threadably engaging the sleeve 18 with the casting 12. As illustrated in FIG. 6, the sleeve end 32 is threaded, as is the inner perimeter of the casting end 34. In FIG. 7, the last rib 40 on the casting I2 is threaded to engage the threads on the nose end 32 of the sleeve insert 18. It is to be understood of course that various combinations of threaded means, welding or braising can be utilized by those skilled in the art in order to suitably interconnect the sleeve 18 within the casting 12.

Referring now to FIG. 8 there is illustrated an alternative construction for a tuyere according to the present invention, wherein the inner surface of the sleeve 18 is provided with a laminated lining. The sleeve 18 includes within its inner face suitable high temperature insulation 54 (such as a A; inch thick insert of Fibrofrax insulation) and a as inch thick, high-temperature alloy sleeve 56 (such as lnconel 702) which can be press fitted into a suitable cavity provided in the sleeve 18. Similar laminated linings for the sleeve 18 can as well be formed of one or more layers of metal in accordance with the teachings of FIG. 8.

Alternative embodiments of the present invention can be readily provided by those skilled in the art following the basic principles of this invention. As an example, an inner sleeve such as the sleeve 18 can be provided with ribs 20 projecting from the outer surface of the sleeve. An outer tubular member with an inner surface can then be provided for engaging the rib ends, thereby forming the passageway.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

I claim:

1. A high velocity multipiece tuyere comprising:

a hollow outer member having an inner face;

inlet and outlet ports on said outer member communicating with said inner face of said outer member for circulating a cooling medium through said member;

a plurality of rib portions projecting from and partitioning said inner face to define a continuous passageway from said inlet to said outlet port, each of said ribs having a free end opposite said inner face;

said passageway being open at the free end of the ribs away from the inner face; and

a hollow inner metal member of dissimilar material than said outer member and having lower heat conductivity than said outer member;

said inner member having inner and outer surfaces and insertable within said hollow outer member; said outer surface sealing engaging said free end of each of said projecting ribs and interconnecting the passageway partitions defined said ribs 'to form a continuous leakproof substantially convolute-shaped passage for said cooling medium which is passed between said inlet and outlet ports when said tuyere is installed in operation in a blast furnace.

2. A high velocity multipiece tuyere as claimed in claim I, wherein said outer member comprises a copper casting, and said inner member is formed of a dissimilar metal having lower heat conductivity than copper to minimize heat loss through the inner member and between the inner surface of said inner member and the coolant in said passages.

3. A high velocity multipiece tuyere as claimed in claim 2, wherein said inner member is formed of stainless steel.

4. A high velocity multipiece tuyere as claimed in claim I, including an insulating liner mounted to the inner surface of said inner member to further reduce the heat loss between said inner surface and the coolant.

5. A high velocity multipiece tuyere as claimed in claim 4, including a high temperature alloy liner mounted to the inner surface of said inner member, said high temperature alloy liner immediately adjacent and overlying said insulating liner.

6. A high velocity multipiece tuyere as claimed in claim 2, wherein said stainless steel inner member has a higher thermal coefficient of expansion than said outer member, thereby insuring said sealing engagement between the outer surface of said inner member and said projecting ribs during normal operation of said tuyere. 

1. A high velocity multipiece tuyere comprising: a hollow outer member having an inner face; inlet and outlet ports on said outer member communicating with said inner face of said outer member for circulating a cooling medium through said member; a plurality of rib portions projecting from and partitioning said inner face to define a continuous passageway from said inlet to said outlet port, each of said ribs having a free end opposite said inner face; said passageway being open at the free end of the ribs away from the inner face; and a hollow inner metal member of dissimilar material than said outer member and having lower heat conductivity than said outer member; said inner member having inner and outer surfaces and insertable within said hollow outer member; said outer surface sealing engaging said free end of each of said projecting ribs and interconnecting the passageway partitions defined said ribs to form a continuous leakproof substantially convolute-shaped passage for said cooling medium which is passed between said inlet and outlet ports when said tuyere is installed in operation in a blast furnace.
 2. A high velocity multipiece tuyere as claimed in claim 1, wherein said outer member comprises a copper casting, and said inner member is formed of a dissimilar metal having lower heat conductivity than copper to minimize heat loss through the inner member and between the inner surface of said inner member and the coolant in said passages.
 3. A high velocity multipiece tuyere as claimed in claim 2, wherein said inner member is formed of stainless steel.
 4. A high velocity multipiece tuyere as claimed in claim 1, including an insulating liner mounted to the inner surface of said inner member to further reduce the heat loss between said inner surface and the coolant.
 5. A high velocity multipiece tuyere as claimed in claim 4, including a high temperature alloy liner mounted to the inner surface of said inner member, said high temperature alloy liner immediately adjacent and overlying said insulating liner.
 6. A high velocity multipiece tuyere as claimed in claim 2, wherein said stainless steel inner member has a higher thermal coefficient of expansion than said outer member, thereby insuring said sealing engagement between the outer surface of said inner member and said projecting ribs during normal operation of said tuyere. 